Vitamin A like few other vitamin is not a single organic chemical compound, instead it is group of different organic compounds which facilitates certain biological functions. Retinol, retinal and four other carotenoids (The carotenes alpha-carotene, beta-carotene, gamma-carotene; and the xanthophyll beta-cryptoxanthin; of which beta carotene is the most important). Vitamin A is important for formation of certain metabolite in the eye, which aids in vision during low light and for color vision. Vitamin A is also important for few other biological functions like formation of epithelial cells and general growth.
Vitamin A – Sources
Vitamin A is present in both plant and animal sources. However the plant sources are better because they offer it primarily in the form of beta carotene (the yellow – orange pigment). The advantage of beta carotene over other forms of Vitamin A is, it is safe even in large quantities unlike other forms which can result in a vitamin overdose and secondly beta carotene is a strong antioxidant and keep our body free from harmful free radicals. Vitamin A is present in abundant quantities in orange-yellow vegetables and fruits like carrots, papaya, mango and so on and also on green leafy vegetables like spinach and other greens.
It is good to take some fat along with these foods as it increases the absorption of this vitamin.
Biological Functions of Vitamin A
Vitamin A is required by the body on an every day basis to maintain healthy skin and to maintain proper eyesight. In addition to this generic function the important biological functions of Vitamin A are:
- Vision (aids both cones and rods, for clear vision under low light as well as color vision)
- Gene transcription
- Immune function
- Embryonic development and reproduction
- Bone metabolism
- Skin and cellular health
- Antioxidant activity (fights free radicals and prevents cancer).
Vitamin A – Requirements and combinations
Vitamin A is a fat soluble vitamin, and will not dissolve in water. This means if fat/oil is not consumed as a part of the diet, then vitamin A will not be absorbed properly by the body. So many people who are on a fat free diet (or low fat diet) are facing vitamin A deficiency. It is also important to consume good amount of protein for better utilization of Vitamin A by the body.
On an average for a normal individual the daily requirement of Vitamin A is around 5,000 (IU). However it varies with age and health. A prolonged deficiency in vitamin A can result in poor vision, poor skin health and also put you at a risk of cancer.
We always recommends natural sources of nutrients. You will never face the risk of over dosage with natural dietary nutrients. However if you don’t have access to fresh vegetables and fruits and other sources rich in vitamin A, you can opt for a supplement. However read more about the risks involved using a supplement before opting for supplements.